/**
 * Copyright (C) 2011 Angelo Zerr <angelo.zerr@gmail.com> and Pascal Leclercq <pascal.leclercq@gmail.com>
 * 
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * 
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS  IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package fr.opensagres.xdocreport.core.registry;

import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.imageio.spi.ServiceRegistry;

import fr.opensagres.xdocreport.core.discovery.IBaseDiscovery;
import fr.opensagres.xdocreport.core.logging.LogUtils;

public abstract class AbstractRegistry<Discovery extends IBaseDiscovery>
{

    /**
     * Logger for this class
     */
    private static final Logger LOGGER = LogUtils.getLogger(AbstractRegistry.class.getName());

    private boolean initialized;

    private final Class<Discovery> registryType;

    public AbstractRegistry(Class<Discovery> registryType) {
        this.registryType = registryType;
    }

    public void initialize() {
        initializeIfNeeded();
    }

    protected void initializeIfNeeded() {
        if (!initialized) {
            onStartInitialization();
            // getClass().getClassLoader() to work under OSGi context
            Iterator<Discovery> discoveries = ServiceRegistry
                    .lookupProviders(registryType, getClass().getClassLoader());
            if (LOGGER.isLoggable(Level.FINE)) {
                LOGGER.fine("discoveries found ? " + discoveries.hasNext());
            }

            while (discoveries.hasNext()) {
                Discovery instance = discoveries.next();
                boolean result = registerInstance(instance);
                if (LOGGER.isLoggable(Level.FINE)) {
                    LOGGER.fine("Registered Discovery instance  " + instance + " " + result);
                }
            }
            onEndInitialization();
            initialized = true;
        }
    }

    /**
     * Method called when registry start initialization.
     */
    protected void onStartInitialization() {

    }

    /**
     * Method called when registry end initialization.
     */
    protected void onEndInitialization() {

    }

    /**
     * Register the instance in the registry.
     * 
     * @param instance
     * @return true if instance cannot be registered and false otherwise.
     */
    protected abstract boolean registerInstance(Discovery instance);

    /**
     * Dispose the registry.
     */
    public final void dispose() {
        doDispose();
        this.initialized = false;
    }

    protected abstract void doDispose();
}
